Overnight people with valid visas cannot re-enter the country - including people with green cards. Later rescinded for green cards holders, but only by a decisions of the Homeland Security secretary, that presumably can change his mind at any time.

Selfishly one could think that this applies only to particular 'special' (so to speak) countries.

Beside being selfish - what happens if a European citizen commit a terrorist act in the US? There are for sure some willing French? Belgian? maybe Italians?

Travel ban for Europeans then - including those with visas? Or travel ban for only one European country - followed by tit-for-tat retaliations from Europe ending up in complete travel freeze?

Yes, not very probable - but at this point who knows? Who can exclude such things?

I think the original meaning was quite specific, referring to thorough changes in the internal structure of code, but now it is used for any and all internal changes that are not meant to change functionality. For example, under ‘refactoring’ Microsoft Visual Studio lists trivial changes like renaming or reordering parameters:

So when someone says ‘I refactored such and such’ it might mean more or less anything, including just changing some method names.

If it is so cheap and easy why no country actually runs on solar and wind? Israel for example: advanced, relatively small, with surely a big interest in not depending on fossil fuels? Or Taiwan? Or Switzerland? All in the clutches of the oil lobby and the Koch brothers?

The best we have are the likes of Germany – not exactly a shining example. Maybe it is due to the famous German disorganization, fecklessness and incompetence and everyone else can do much better?